Techniques for designing and manufacturing in-ear hearing-aid devices typically need to be highly customized in both internal dimensions to support personalized electrical components to remedy a individual's particular hearing loss need, and in external dimensions to fit comfortably and securely within an ear canal of the individual. Moreover, cosmetic considerations also frequently drive designers to smaller and smaller external dimensions while considerations of efficacy in hearing improvement typically constrain designers to certain minimal internal dimensions notwithstanding continued miniaturization of the electrical components.
FIG. 1 illustrates a conventional production process flow 10 for manufacturing customized in-ear hearing-aid devices. As illustrated by Block 12, a positive mold of an ear canal of a subject is generated along with a negative mold that may be used for quality assurance by acting as the “ear” of the subject when testing a finally manufactured hearing-aid shell. As will be understood by those familiar with conventional hearing-aid manufacturing techniques, the positive mold may be generated by an audiologist after performing a routine hearing examination of the subject and the negative mold may be generated by a manufacturer that has received the positive mold and a request to manufacture a customized hearing-aid shell. Referring now to Block 14, a detailed positive mold of a hearing-aid shell may then be generated by the manufacturer. This detailed positive mold may be generated by manually sculpting the positive mold to a desired size suitable for receiving the necessary electrical components to remedy the defective auditory condition of the subject. A detailed shell cast is then formed from the detailed positive mold, Block 16, and this shell cast is used to form a plastic hearing-aid shell, Block 18.
As illustrated by Block 20, a vent structure may then be attached (e.g., glued) to an inner surface of the plastic hearing-aid shell. Manual trimming and surface smoothing operations may then be performed, Block 22, so that the shell is ready to receive a faceplate. The faceplate may then be attached to a flat surface of the shell and then additional trimming and smoothing operations may be performed to remove abrupt edges and excess material, Block 24. The electrical components may then be added to the shell, Block 26, and the shape of the resulting shell may be tested using the negative mold, Block 28. A failure of this test typically causes the manufacturing process to restart at the step of generating a detailed positive mold, Block 14. However, if the manufactured shell passes initial quality assurance, then the shell with electrical components may be shipped to the customer, Block 30. Steps to fit and functionally test the received hearing-aid shell may then be performed by the customer's audiologist. A failure at this stage typically requires the repeat performance of the process flow 10 and the additional costs and time delay associated therewith.
Unfortunately, these conventional techniques for designing and manufacturing customized in-ear hearing-aid devices typically involve a large number of manual operations and have a large number of drawbacks. First, manual hearing-aid shell creation through sculpting is error prone and considered a main contributor in a relatively high customer rejection rate of 20 to 30%. Second, the typically large number of manual operations that are required by conventional techniques frequently act as a bottleneck to higher throughput and often limit efforts to reduce per unit manufacturing costs. Accordingly, there exists a need for more cost effective manufacturing operations that have higher throughput capability and can achieve higher levels of quality assurance.